drm/vmwgfx: Fix gem refcounting and memory evictions

v2: Add the last part of the ref count fix which was spotted by
Philipp Sieweck where the ref count of cpu writers is off due to
ERESTARTSYS or EBUSY during bo waits.

The initial GEM port broke refcounting on shareable (prime) surfaces and
memory evictions. The prime surfaces broke because the parent surfaces
weren't increasing the ref count on GEM surfaces, which meant that
the memory backing textures could have been deleted while the texture
was still accessible. The evictions broke due to a typo, the code was
supposed to exit if the passed buffers were not vmw_buffer_object
not if they were. They're tied because the evictions depend on having
memory to actually evict.

This fixes crashes with XA state tracker which is used for xrender
acceleration on xf86-video-vmware, apps/tests which use a lot of
memory (a good test being the piglit's streaming-texture-leak) and
desktops.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Fixes: 8afa13a0583f ("drm/vmwgfx: Implement DRIVER_GEM")
Reported-by: Philipp Sieweck <psi@informatik.uni-kiel.de>
Cc: <stable@vger.kernel.org> # v5.17+
Reviewed-by: Maaz Mombasawala <mombasawalam@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220420040328.1007409-1-zack@kde.org

1 files changed, 20 insertions, 23 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
index 31aecc46624b..04c8a378aeed 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
@@ -46,6 +46,21 @@ vmw_buffer_object(struct ttm_buffer_object *bo)
 	return container_of(bo, struct vmw_buffer_object, base);
 }
 
+/**
+ * bo_is_vmw - check if the buffer object is a &vmw_buffer_object
+ * @bo: ttm buffer object to be checked
+ *
+ * Uses destroy function associated with the object to determine if this is
+ * a &vmw_buffer_object.
+ *
+ * Returns:
+ * true if the object is of &vmw_buffer_object type, false if not.
+ */
+static bool bo_is_vmw(struct ttm_buffer_object *bo)
+{
+	return bo->destroy == &vmw_bo_bo_free ||
+	       bo->destroy == &vmw_gem_destroy;
+}
 
 /**
  * vmw_bo_pin_in_placement - Validate a buffer to placement.
@@ -615,8 +630,9 @@ int vmw_user_bo_synccpu_ioctl(struct drm_device *dev, void *data,
 
 		ret = vmw_user_bo_synccpu_grab(vbo, arg->flags);
 		vmw_bo_unreference(&vbo);
-		if (unlikely(ret != 0 && ret != -ERESTARTSYS &&
-			     ret != -EBUSY)) {
+		if (unlikely(ret != 0)) {
+			if (ret == -ERESTARTSYS || ret == -EBUSY)
+				return -EBUSY;
 			DRM_ERROR("Failed synccpu grab on handle 0x%08x.\n",
 				  (unsigned int) arg->handle);
 			return ret;
@@ -798,7 +814,7 @@ int vmw_dumb_create(struct drm_file *file_priv,
 void vmw_bo_swap_notify(struct ttm_buffer_object *bo)
 {
 	/* Is @bo embedded in a struct vmw_buffer_object? */
-	if (vmw_bo_is_vmw_bo(bo))
+	if (!bo_is_vmw(bo))
 		return;
 
 	/* Kill any cached kernel maps before swapout */
@@ -822,7 +838,7 @@ void vmw_bo_move_notify(struct ttm_buffer_object *bo,
 	struct vmw_buffer_object *vbo;
 
 	/* Make sure @bo is embedded in a struct vmw_buffer_object? */
-	if (vmw_bo_is_vmw_bo(bo))
+	if (!bo_is_vmw(bo))
 		return;
 
 	vbo = container_of(bo, struct vmw_buffer_object, base);
@@ -843,22 +859,3 @@ void vmw_bo_move_notify(struct ttm_buffer_object *bo,
 	if (mem->mem_type != VMW_PL_MOB && bo->resource->mem_type == VMW_PL_MOB)
 		vmw_resource_unbind_list(vbo);
 }
-
-/**
- * vmw_bo_is_vmw_bo - check if the buffer object is a &vmw_buffer_object
- * @bo: buffer object to be checked
- *
- * Uses destroy function associated with the object to determine if this is
- * a &vmw_buffer_object.
- *
- * Returns:
- * true if the object is of &vmw_buffer_object type, false if not.
- */
-bool vmw_bo_is_vmw_bo(struct ttm_buffer_object *bo)
-{
-	if (bo->destroy == &vmw_bo_bo_free ||
-	    bo->destroy == &vmw_gem_destroy)
-		return true;
-
-	return false;
-}